// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_VIEWS_DRAG_CONTROLLER_H_
#define UI_VIEWS_DRAG_CONTROLLER_H_

#include "ui/views/views_export.h"

namespace gfx {
class Point;
}

namespace ui {
class OSExchangeData;
}

namespace views {
class View;

// DragController is responsible for writing drag data for a view, as well as
// supplying the supported drag operations. Use DragController if you don't
// want to subclass.
class VIEWS_EXPORT DragController {
public:
    // Writes the data for the drag.
    virtual void WriteDragDataForView(View* sender,
        const gfx::Point& press_pt,
        ui::OSExchangeData* data)
        = 0;

    // Returns the supported drag operations (see DragDropTypes for possible
    // values). A drag is only started if this returns a non-zero value.
    virtual int GetDragOperationsForView(View* sender,
        const gfx::Point& p)
        = 0;

    // Returns true if a drag operation can be started.
    // |press_pt| represents the coordinates where the mouse was initially
    // pressed down. |p| is the current mouse coordinates.
    virtual bool CanStartDragForView(View* sender,
        const gfx::Point& press_pt,
        const gfx::Point& p)
        = 0;

protected:
    virtual ~DragController() { }
};

} // namespace views

#endif // UI_VIEWS_DRAG_CONTROLLER_H_
